1. Field of the Invention
The present invention relates to lighting systems used in signs. In particular, the present invention relates to light sockets used in the lighting systems of indoor and outdoor signs generally observed at commercial establishments. More particularly, the present invention relates to light sockets used in connecting standard-size fluorescent light tubes within indoor and outdoor signs. Yet more particularly, the present invention relates to light sockets used in connecting standard-size fluorescent light tubes which can be adapted to fit within any indoor or outdoor sign, regardless of the shape or size of the light.
2. Description of the Prior Art
Tubular lamp sockets have been around since the development of tubular lamps. The earliest type of socket was designed to accept a fluorescent lamp having two spaced prongs at each end. These sockets were generally circular in design and were connected to a flat surface of a socket support bracket. As the demand for fluorescent lighting systems increased, newer sockets were designed which resulted in the standardization of the light socket. A "tombstone" design was one such standard design. Its name was derived from the socket's appearance. When viewed from one end, the light sockets look like miniature tombstones extending from the sockets' supporting members. This "tombstone" design allowed for the economical manufacturing of various lamp fixture designs.
Because fluorescent lights use less electricity, operating costs are reduced relative to the cost of standard incandescent lighting. This created a relatively large increase in the demand for lighted signs in the commercial marketplace. The basic characterization of lighted signs is that they are all custom-made or extruded signs made of glass, plastic, metal, or any combination of the three, using fluorescent light tubes inside as the means for lighting the sign. The signs are typically made with an aluminum frame housing to which opaque glass or plastic casings are attached. The fluorescent lamp is placed within the casing. Until recently, these signs were usually custom-made, rather than extruded or pre-fabricated in standard sizes. That is, they were, and for the most part, continue to be, made to meet a particular appearance specification. Fluorescent tubular lamps, on the other hand, do come in standard sizes. Since the size of the aluminum frame and the size of the standard tubes rarely match, it is usually necessary to create essentially unique housings for each tubular lamp so as to adapt the standard-size tubular lamps within the sign casing in a manner to ensure complete illumination of the sign. Given the size of such signs, it is often necessary to include light socket support brackets in conjunction with the housings to ensure stability of the tubular lamps therein. These support brackets are generally custom-made for each particular tubular-lamp socket and each sign may require a variety of custom-made support brackets.
Although there have been some minor changes in the original lamp socket design based on the lamps having a pair of spaced prongs at opposite ends thereof, these changes focused primarily on the type of contacts used for connecting the lamps to a power source. Other design efforts concentrated on the ability to adjust the position of the socket along the socket-support bracket; that is, the light socket and the support bracket were made to allow a unilateral, perpendicular adjustment of the tubular lamp.
U.S. Pat. No. 3,562,511 (1971, Reeves) teaches an elongated socket-supporting element for assembly in a fluorescent lighting fixture. The socket-supporting element of the Reeves device includes a plurality of elongated, aligned, spaced-apart socket guide holes and slidable plates, each having a fluorescent lamp socket, covering each hole. The elongated, socket guide holes allow sliding of the slidable plates toward or away from each other for accommodating the various terminal spacings of conventional U-shaped, hot-cathode fluorescent lamp tubes.
U.S. Pat. No. 4,420,798 (1983, Herst et al.) teaches an adjustable, overhead lighting fixture. The Herst device includes fixed, elongated support runners and a plurality of elongated hanger-fixture elements supported on their ends by any two support runners. The elongated hanger-fixture elements span any two support runners at any point along the length of the runners and are electrified from the runners.
As indicated, these prior sign devices are limited to (1) the structural design of the standard lighting fixture, (2) the structural design of a lamp socket such as the circular or "tombstone" designs, and (3) the artistic appearance of the sign itself. Because of these limitations, all of the prior art devices suffer from the same disadvantages inherent in their designs. Most notable is the cost of manufacturing custom-made signs attributed to the use of currently existing fluorescent lamp sockets. The options available to the sign manufacturer are either (1) to use the standard, straight fluorescent light tubes in a vertical or horizontal arrangement within a "standardized" pre-fabricated sign housing, (2) to use commercially available U-shaped light tubes, or (3) to make a custom sign housing. The disadvantage of option 1 is that a custom-made adapter for a tubular lamp socket is required. Fabrication of each adapter and housing is labor intensive because each one is generally different and each must meet UL lighting standards. These custom-made sockets are specifically designed for the particular sign under construction and entail taking account of the precise layout and fitting of the adapter housing. No allowance can be tolerated for a crooked socket. Consequently, the cost of designing and manufacturing an extruded sign using the standard fluorescent tubes is prohibitive under this option. The alternative is option 2. Unfortunately, the U-shaped tubes are much more expensive than the standard tubes. Again, this added cost makes the custom signs more expensive than they ought to be. A third option to the sign manufacturer, which is not economically efficient, is to make a custom sign housing. None of the prior art devices have addressed this particular aspect of the cost of manufacturing signs of this type. In most cases, the extra costs associated with the use of U-shaped fluorescent tubes and/or custom housings are simply passed along to the customer.
Therefore what is needed is a commercial lighting system that permits the use of standard-size fluorescent light tubes-instead of the more expensive U-shaped tubes-in any type of pre-fabricated or custom-made sign. What is still further needed is a lighting system that provides a fluorescent-tube socket that is adjustable to any angle and height relative to the socket-support bracket, thus allowing one to use the standard, straight, fluorescent-tube lamps regardless of housing size and shape. Finally, what is needed is a commercial lighting system that is inexpensive relative to present arrangements and that is relatively easy to install.